Lock-stitch sewing machines



Oct. 7, 1958 I K. NICOLAY 2,854,936

LOCK-STITCH SEWING MACHINES Filed Sept. 9, 1954 2 Sheets-Sheet 1 4 I 2 .1 2,, '7 Fig. 7 v v I 20/ 8 4 k I 3o 7 haven/or 3 g Y'EWMZQ i azzw Oct. 7, 1958 K. NICOLAY 5 6 LOCK-STITCH SEWING MACHINES Filed Sept. 9, 1954 2 Sheets-Sheet 2 INVENTOR.

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United States Patent Ofiice 2,854,936 Patented Oct. 7, 1958 LOCK-STlTCI-I SEWING MACHINES Karl Nicolay, Bielefeld, Germany, assignor to Durkoppwerke Airtiengeselischaft, Bielefeld, Germany, a corporation of Germany Application September 9, 1954, Serial No. 454,894

Claims priority, application Germany September 14-, 1953 16 Claims. (Cl. 112-464) In the carrying out of corner stitching on two-needle lock-stitch machines, the needle producing the inner row of stitches is put out of operation by fixing it on its upper position or'by turning it aside and the other needle continues stitching for a distance corresponding to the space between the two needles, then the corner is turned and said other needle continues stitching alone, again for a distance equal to the space between the needles, whereafter both needles are brought into operation again.

A disclosure, such as the Erase Patent #l,676,853, issued July 10, 1928, teaches the feature of a two-needle machine wherein one of the needles may be rendered inoperative.

During the time that the inner needle is out of action, the further forward movement of the sewing material causes a length of thread to be drawn from the lower thread bobbin which is associated with the inoperative needle, which thread is not used in sewing. On both needles coming into action again, this unused thread forms a loop at the inner corner, the elimination of which, for the production of neat work, is very desirable, but this however has not been possible up till now without additional manual work.

This defect is obviated by the present invention by the use of -a device incorporated in the machine and operated from outside, which makes it possible to rewind the unused lower thread on to the bobbin in the bobbin casing.

The invention provides mechanism operable by the operator of a machine for rewinding on to a bobbin of an inoperative needle unused thread which has been drawn from the bobbin during the time said needle has been inoperative, and according to novel features of the invention such unused thread is rewound on to a bobbin by reverse rotation thereof brought about by driving means which is normally inoperative.

The invention also provides a method of operation of a two-needle lock-stitch machine for stitching sharp corners wherein, after a period of stitching by one needle only, during which unused thread has been drawn from the bobbin below the other needle, such unused thread is rewound on to the bobbin by a reverse rotation of the bobbin through driving means normally in an inoperative position.

The means for re-winding the unused lower thread on to the bobbin is held normally in a non-operative position by means of a spring, and is swung into the working position, and set in operation by means of a single hand crank.

According to a further feature of the invention, the. movement transmission from the hand crank is imparted to two shafts separately via slip clutches which are so loaded that they transmit only the forces necessary for the functions of the respective shafts, so that breaking of the thread is avoided. One shaft may be formed as a hollow shaft surrounding the other shaft concentrically and having at its upper end a head plate and at its lower end the hand crank. The hand crank is in addition movably connected to the driving shaft via a lever arm. This driving shaft has at its upper end a driving wheel which is in working connection with an intermediate wheel located on the said head plate of the pivot shaft. The intermediate wheel transmits the turning movement imparted to it by the driving wheel after pivoting in of the device, to the lower thread bobbin lying in the bobbin casing.

One embodiment of the invention is illustrated in the accompanying drawing, wherein:

Fig. 1 shows a vertical longitudinal section through the front part of the bottom portion of a sewing machine;

Fig. 2 is a plan view of the mechanism shown in Fig. 1;

Fig. 3 shows the pattern of the lower thread in a stitched corner as carried out in the usual two-needle quilt stitching machine;

Fig. 4 is a perspective view of a bobbin casing with bobbin; and

Fig. 5 is a sectional front view of a sewing machine head to illustrate a known arrangement for sewing with one or two needles selectively.

1 indicates the bottom plate or base of a two-needle lock-stitch machine. This base has a cut out portion 2 which in the sewing area is covered by a needle plate 3 with openings 4 for the passage of the usual feeder and holes 5 for the passage of the needles. A slide 6 adjoins the needle plate 3 for closing the remainder of the opening 2 which slide is omitted in Fig. 2.

A horizontally-rotating loop-taker 7 for a left-hand stitching unit is located in a bracket 8 arranged under the said base plate 1 and is driven in known manner via a skew gear wheel 9. A bobbin casing 10 is located in the loop-taker '7, which casing holds the lower thread bobbin 11. These parts are present in the same or similar form and arrangement in every lock-stitch machine.

The device for the re-winding of the unused lower thread has .an outer bearing sleeve 12 which is fixed on the said bracket 8 by means of a foot 13. A hollow shaft 14 is mounted in the bearing sleeve 12, which shaft carries at its upper end a head plate 15. On the lower end of the hollow shaft 14 is a hand crank or control member 16 which is coupled to the hollow shaft only by means of a spring-loaded friction disc or pad 17 acting as a primary slip clutch. The tension ofthe compression spring 18 is adjustable by means of an adjusting screw 19.

A solid spindle 20 is introduced through the hollow shaft 14 and carries at its upper end a milled edged driving wheel 21. The spindle 2i and hollow shaft 14 constitute inner and outer co-axial members. On the lower end of the shaft a lever 23 is rotatable between friction discs 22 which constitute a secondary slip clutch. The lever is in movable contact with the hand crank 16.

The hollow shaft 14, with the head plate 15 firmly connected to it, is normally held in the neutral position (shown in dot and dash lines in Fig. 2) by means of a coil spring 24 which surrounds the bearing sleeve 12 and is under a turning stress. The spring 24 for this purpose engages with one spring end 25 in the head plate 15 and the other spring end 26 engages the base plate 1. The working position of the device, shown in full lines in Fig. 2, is limited by means of an adjusting screw 27 which is provided in a downwardly bent lug 28 of the head plate 15.

On the head plate 15 is located an intermediate idler wheel 29 which is in driving connection with the driving wheel 21 on the shaft 26. The intermediate wheel 29 is for example formed from a rubber disc which is inserted between upper and lower metal clamping discs. The turning movement of the inner shaft 20 is transmitted via the intermediate wheel 29 to the lower thread bobbin 11, the milled edge of which upon operation of the device comes into driving connection with the intermediate wheel 29. The bobbin casing 10 has an opening 30 for the entry of the intermediate Wheel 29.

In Fig. is illustrated one known construction whereby one of two needles normally working togethermay be held out of operation whenever necessary. Such an illustraton is to be found in the aforementioned patent to Wilhelm Brase, #l,676,853, issued July 10, 1928, and tilted Sewing Machines With Several Needles. Needle bar 31 is driven at all times bythe connecting rod 32 and crank disc 33. Saidneedlebar has a yoke member 34 at its top end. The other needle bar 35 is rotatable inits bearings. It has a lug 36 at itstop end which, on the one hand, may enter said yoke 34, wherebythe needle bar isdriven alongwith its fellow (as shown) or, on the other hand, the needle bar may be rotated so as to be disengagedfromsaid yoke 34 and entered into a further yoke 37 mounted, on a rod 38 which is fixedly carried by the head of the machine. In this .position, the needle bar is held out of action.

During the stitching of corners on the usual two-needle lock-stitch machine, the left-hand needle (innermost of the corner) is put out of operation and the other operating needle continues stitching for a distance equal to that between the needles, then the corner is turned and the one needle again stitches alone for the said distance. By the forward movement of the sewing material during the stitching by the operating needle a corresponding length of lower thread is drawn from the left-hand lower thread bobbinsuch as 11 below the stationary needle, which length of thread is not used for stitching purposes and, on re-starting of the left-hand needle, the thread remains as a loop in the corner of the inner row of stitching. as illustrated in Fig. 3.

In order to wind back this unsewn piece of thread, the hand crank 16 of the device according to the invention isturned anti-clockwise (Fig. 2). By means of the primary slip clutch 17, the hollow shaft 14 is turned and the head plate 15 with the intermediate wheel 29 located on it is turned as far as the stop 27 allows. In this position the intermediate wheel 29 comes into driving connection with the milled edge of the lower thread bobbin 11. If the hand crank is now turned further in the same direction it turns the shaft 20 via the secondary slip clutch 22 and lever 23, and the driving wheel 21 located on samesets the intermediate wheel 29 in motion, which in its turnrotates the bobbin 11 in the direction indicated. Thus the length of lower thread not used in sewing is again wound on to the bobbin 11 so that the undesirable loop formation is done away with. Upon releasing the hand crank 16 the spring24 comes into action and swings the hollow shaft 14 with the head plate 15 into the neutral position again.

The slip clutches between the hand crank 16 and the hollow shaft 14 as well as that between the lever 23 and the shaft 20 are so proportioned that the transmitting forces are only sufficient for the pivoting of the device and for the winding back of the unused length ofthread.

The precise constructional form and arrangement of the device depends on the structure of the particular machine to which it is to be added. The construction illustrated anddescribed is a preferred embodiment.

What I claim is:

1. Manually operable mechanism for a lock-stitch sewing machine for rewinding a thread onto a rotatable bobbin unwound therefrom during the inoperativeness of .a needle for the bobbin comprising, a head plate oscillatable between operative and inoperative positions, actuating means carried by said head plate for engaging and rotating the bobbin in the operative position of said head plate for the rewinding of the thread onto the bobbin, spring means holding said head plate in inoperative position,' and means for oscillating said head plate to operative position and for operating said actuating means.

2. Manually operable mechanism for a lock-stitch sewing machine for rewinding a thread onto a rotatable bobbin unwound therefrom during the inoperativeness of .a needle for the bobbin comprising, a head plate oscillatable between inoperative and operative bobbin rewinding rotating positions, spring means yieldingly holding said head plate in the inoperative position, bobbin rotating means carried by said head plate to engage and rotate the bobbin, manually operable means arranged to oscillate said head plate to operative position and thereafter to operate said bobbin rotating means, and stop means to arrest the movement of said head plate to its operative position.

3. Manually operable mechanism for a two-needle lockstitch sewing machine adapted to rewind onto a bobbin a thread unwound therefrom during inoperativeness of a corresponding needle and operation of the other needle as a work-piece being stitched traverses a corner thereby to avoid looping of the unwound thread comprising, a head plate oscillatable between inoperative and opera-tive bobbin rewinding rotating positions, spring means yieldingly holding said head. plate in inoperative position, bob bin rotating means carried by said head plate to engage and rotate the bobbin, manually operable means arranged to oscillate said head plate to operative position and thereafter to operate said bobbin rotating means, and stop means to arrest movement of said head plate to its operative position.

4. Mechanism as set forth in claim 3 wherein said manually operable .means includes, inner and outer co axial members, a handle attached to one of said co-axial members, a primaryslip clutch disposed between said handle andsaid outer. co-axial member, a secondary slip clutch between said handle and said inner co-axial member, said slip clutchesbeing arranged whereby said handle oscillates said head plate to operative position and thereafter said inner co-axial member is rotated to rotate said bobbin rotating means.

5. Mechanism as set forth in claim 3 wherein, said manually operable means includes, inner and outer coaxial members, a handle, a slip clutch between said handle and outer member, a slip clutch between said handle and inner member, said clutch members being arranged whereby said handle oscillates said head plate to operative position and thereafter said inner member is rotated to rotate said bobbin rotating means.

6. .Manually operable mechanism for a lock-stitch sewingmachine for rewinding a thread onto a rotatable bobbin unwound therefrom during inoperativeness of a needle for'the bobbin comprising, relatively rotatable inner and outer co-axial members, a head plate fixed on said outer member, bobbin engaging and rotating means disposed on said head plate and actuated by said inner member, said outer member being oscillatable between inoperative position and operative positions of said head plate wherein said bobbin rotating means is in engagement with the bobbin, means limiting movement of said head plate to operative position, means urging said outer member and head plate to inoperative positions, a handle, and separate clutch means connecting said handle to said inner and outer members whereby by means of said handle said outer member and head plate are oscillated to operative positions and thereafter said inner member is rotated to actuate said bobbin rotating means.

7. Manually operable mechanism for a lock-stitch sewing machine for rewinding a thread onto a rotatable bobbin unwound therefrom during inoperativeness of a needle for the bobbin comprising, a support, a bracket secured to said support and having a tubular shaft oscillatable on .avertical axis therein and having a horizontally. disposed head plate on the upper end thereof, a resilient wheel rotatable on the head plate to engage and rotate a-bobbin, a spindle rotatable in the shaft having a driving wheel in engagement with said resilient wheel, a handle rotatable on the shaft and a slip clutch between the shaft and said handle whereby the head vplate may be oscillatedby said handle from inoperative to operative position for uzuk I: U engagement of said resilient wheel with a bobbin, means limiting movement of the head plate to operative position, a member rotatable on said spindle, and a slip clutch between said spindle and rotatable member engageable by said handle as said handle is rotated to position the head plate in operative position whereupon said slip clutch slips to permit continued rotation of said handle to rotate said spindle through a second clutch.

8. Manually operable mechanism for a lock-stitch sewing machine for rewinding a thread onto a rotatable bobbin unwound therefrom during inoperativeness of a needle for said bobbin comprising, a support, a bracket secured to said support and having a tubular shaft oscillatable on a vertical axis therein, the tubular shaft being provided with a horizontally disposed head plate on the upper end thereof, a resilient wheel rotatable on the head plate to engage and rotate a bobbin, a spindle rotatable in the tubular shaft and having a driving wheel in engagement with said resilient wheel, a handle rotatable on the tubular shaft and a slip clutch between the shaft and said handle whereby the head plate may be oscillated by said handle from inoperative to operative position for engagement of said resilient wheel with a bobbin, means limiting movement of the head plate to operative position, a member rotatable on said spindle and a slip clutch between said spindle and member engageable by said handle as said handle is rotated to position the head plate in operative position whereupon said first named clutch slips to permit continued rotation of said handle to rotate said spindle through the second clutch, and means biasing the shaft and head plate to inoperative positions.

9. Manually operable mechanism for a two-needle lock-stitch sewing machine adapted to rewind onto a bobbin a thread unwound therefrom during inoperativeness of a corresponding needle and operation of the other needle as a work-piece being stitched traverses a corner thereby to avoid looping of the unwound thread comprising, a head plate oscillatable between operative and inoperative positions, actuating means carried by said head plate for engaging and rotating the bobbin in operative position of said head plate, spring means holding said head plate in operative position, and means for oscillating said head plate to operative position and for operating said actuating means.

10. Manually operable mechanism for a two-needle lock-stitch sewing machine adapted to rewind onto a bobbin a thread unwound therefrom during inoperativeness of a corresponding needle and operation of the other needle as a work-piece being stitched traverses a corner thereby to avoid looping of the unwound thread, comprising, relatively rotatable inner and outer co-axial members, a head plate fixed on said outer member, bobbin engaging and rotating means on said head plate actuated by said inner member, said outer member being oscillatable between an inoperative position and an operative position of said head plate wherein said bobbin rotating means is in engagement with the bobbin, means limiting movement of said head plate to operative position, means urging said outer member and head plate to inoperative position, a handle, and separate clutch means connecting said handle to said inner and outer members whereby by means of said handle said outer member and head plate are oscillated to operative position and thereafter said inner member is rotated to actuate aid bobbin rotating means.

11. Manually operable mechanism for a two-needle lock-stitch sewing machine adapted to rewind onto a bobbin a thread unwound therefrom during inoperativeness of a corresponding needle and operation of the other needle as a work-piece being stitched traverses a corner thereby to avoid looping of the unwound thread comprising, a support, a bracket secured thereto having a tubular shaft oscillatable on a vertical axis therein provided with a horizontally disposed head plate on the upper end thereof, a resilient wheel rotatable on the head plate to engage and rotate a bobbin, a spindle rotatable in the said spindle and member engageable by said handle as said handle is rotated to position the head plate in operative position whereupon said first named clutch slips to permit continued rotation of said handle to rotate said spindle through said second named clutch.

12. Manually operable mechanism for a two-needle lock-stitch sewing machine adapted to rewind onto a bobbin a thread unwound therefrom during inoperativeness of a corresponding needle and operation of the other needle as a work-piece being stitched traverses a corner thereby to avoid looping of the unwound thread comprising in combination, a support, a bracket secured to said support and having a tubular shaft oscillatable on a vertical axis therein horizontally disposed head plate on the upper end of said shaft, a resilient wheel rotatable on said head plate to engage and rotate a bobbin, a spindle rotatable in the tubular shafit and having a driving wheel in engagement with said resilient wheel, a handle rotatable on the tubular shaft and a slip clutch between the tubular shaft and said handle whereby said head plate may be oscillated by said handle from inoperative to operative position for engagement of said resilient wheel with a bobbin, means limiting movement of said head plate to operative position, a member rotatable on said spindle and a slip clutch between said spindle and member engageable by said handle as said handle is rotated to position said head plate in operative position whereupon said first named clutch slips to permit continued rotation of said handle to rotate said spindle through said second named clutch, and means biasing said shaft and head plate to inoperative position.

13. In a two-needle lock-stitch machine with means for holding an inner needle temporarily out of action while the outer needle is operative, the improvement compris ing, means operable at the will of the user for re-winding onto a bottom bobbin below the inner needle rendered inoperative, a thread which has been drawn from the bottom by the traverse of the material during the continued operation of the outer needle.

. 14. In a two-needle lock-stitch machine including means for holding one needle temporarily out of action, the improvement comprising, re-winding means being operable at the will of the user for re-winding onto a bottom bobbin below the inoperative needle a thread drawn from the bobbin by the traverse of the material during the continued operation of the other needle, said re-winding means including a control member and spring means normally holding said control member inoperative wherein a first movement of said control member against the resistance of said spring brings said re-winding means into operative position and a second movement causes said re-winding means to operate.

15. In a two-needle lock-stitch machine having means for holding one needle temporarily out of action, the improvement comprising, re-winding means operable at the will of the user for re-winding onto a bottom bobbin below the needle which has been rendered inoperative a thread which has been drawn from the bobbin by the traverse of the material during the continued operation of the other needle, said re-Winding means including a rotary control member and driving and driven members carried by said control member and spring means normally holding said control member inoperative wherein a first rotary movement of said control member brings said driven member into engagement with the bottom bobbin without being driven and a continued rotary move- 7 V mentof said control member canses said driving member to operate said driven member to rotate the bobbin. a

16. In a mechanism for a lock-stitch sewing machine for holding-an inner needle temporarily inoperative while the outer needle is operative, the improvement compris- 5 the rewinding of the thread onto the bobbin, yielding 10 8 sping means holding said head plate in the inoperative position; and means for oscillating said head plate to operative position and for operating said actuating means.

. References Citedin the file of this patent UNITED STATES PATENTS Brase July 10, 1928 Stephenson Feb. 24, 1931 

